Flashcards
waves
Flashcards do conjunto (57)
- 1define Longitudinal Wavesare waves in which the direction of vibration of the particles is parallel to the direction in which the waves travels.
- 2define transverse wavesare waves in which the direction of vibration is perpendicular to the direction in which the waves travel.
- 3name all the electromagnetic wavesradio waves, microwaves, infrared radiation, visible light,ultraviolet radiation, x-ray and gamma radiation.
radio waves have the lowest frequency and the longest wavelength.
gamma waves have the highest frequency and the shortest wavelength - 4give 3 examples of longitudinal wavessound waves
primary seismic waves
compression waves on a slinky toy - 5give 3 examples of transverse waveselectromagnetic waves
secondary seismic waves
waves on a string - 6define polarised wavesa wave that oscillates in one direction only. up and down or left to right. they are transverse waves
- 7what happens if light is passed through two polarising filters at right angle to each other?The first filter will polarise the wave and this polarised wave cannot pass through the second filter because the alignment of the second is at 90 degrees.
- 8example of polarisation in the real worldsunglasses lens are polarised to reduce glare of light reflected by water or glass. the reflected light is polarised and the intensity is reduced.
- 9define displacement in a wave graphof a vibration particle its distance and direction from its equilibrium position.
- 10define amplitudethe maximum displacement of a vibrating particle. for a transverse wave, this is the height of a wave crest or depth of a wave trough from its equilibrium.
- 11wavelengththe least distance between two adjacent vibrating particles with the same displacement and velocity at the same time. e.g. distance between adjacent crest.
- 121 oscillation / 1 cyclefrom maximum displacement to the next maximum displacement
- 13the periodthe time it takes to complete 1 oscillation
- 14the frequencythe number of oscillation passing a point in a second
- 15wave speed formulaspeed = frequency x the wavelength
- 16define phase difference between two particles vibrating at the same frequencythe fraction of a cycle between the vibration of the two particles, measured in radians or degrees.
- 17what are reflection waveswaves that bounce back when they hit a boundary.
- 18what are refraction waveswaves changes direction as it enters a different medium. the change in direction is a result of the wave slowing down or speeding up. also the wavelength changes.
frequency stays constant. - 19diffracted waveswave spread out as it passes through a gap or round an obstacle
- 20when light from a more optically dense substance passes into a less optically dense substance, where would the light ray bend?away from the normal
- 21when light from a less optically dense substance passes into a more optically dense, where would the light ray bend?towards the normal
- 22formula for snells law
- 23under what conditions does snells law applyit applies to monochromatic light. travelling from one medium into another medium.
- 24when are stationary waves created?stationary waves are created when two progressive waves of the same frequency and amplitude are moving in opposite directions superpose.
- 25define nodea fixed point in a stationary wave pattern where the amplitude is zero
- 26define antinodefixed point in a stationary wave pattern where the amplitude is a maximum.
- 27what is the distance between two adjacent nodeshalf a wavelength
- 28things you know about the fundamental frequency / first harmonic.the stationary wave is vibrating at its lowest possible resonant frequency.
it has a loop with a node at each end
the wavelength is double the length of the string
wavelength = 2 length - 29things you know about the second harmonicit has twice the first harmonics frequency there are two loops with a node in the middle and one on each end.
the wavelength is = to the length of the string. - 30things you know about the third harmonicits three times the first harmonics frequency. it has two nodes in the middle and one on each end.
the wavelength is = 3/2 the length of the string. - 31the formula for frequency of the firsts harmonic
- 32explain why a glass prism splits white light into the colours of the spectrum.white light is composed of light with a continuous range of wavelengths. the glass prism refracts light by different amounts depending on its wavelength. the shorter the wavelength in air the greater the amount of refraction. so each colour in the white light is refracted by different amount.
the dispersion effect occurs because the speed of light depends on the wavelength. - 33when would Total internal reflection occurwhen the angle of incidence is greater than the critical angle.
the incidence substance has a larger refractive index than the other substance. - 34why do diamonds sparklewhen white light enters a diamond, it is split into colours of the spectrum. diamonds have a high refractive index so it separates the colours more than any other substance does. light ray in a diamond may be TIR many times before it emerges, which means the colour spreads out more and more.
so the diamond sparkles with different colours. - 35advantages of claddingprotects the surface of the core
prevents cross-over between adjacent fibres - 36why is the cladding necessaryTIR takes place at the core-cladding boundary so light rays stay in the core. if two fibres are in contact light would cross from one fibre to the other if no cladding was there.
- 37why must the core be narrowto prevent modal dispersion. this occurs in wide cores because light travelling along the axis travels a shorter distance per metre of fibre than light that constant undergoes TIR. the light that undergoes TIR if long enough might emerge with the next pulse.
- 38define coherenttwo sources of waves are coherent if they emit waves with constant phase difference and frequency.
- 39why is a single slit used in young's double slit experimentto act as a point source diffracting light to both slits
- 40what happens if the single slit is too widethe dark fringes become narrower than the bright fringes, and contrast is lost between the dark and bright fringe.
- 41in young's double slit experiment when are bright and dark fringes formedbright fringes (constructive) occur when the waves are in phase and superpose and the distance travelled by the waves must be a whole number of wavelengths.
the dark fringes (destructive) occur when the waves are out of phase and the distance travelled by the waves must be exactly half of a wavelengths. - 42what is fringe spacingthe distance from the centre of a dark fringe to the centre of the next dark fringe.
- 43formula for fringe spacing
- 44define monochromatic lightlight of the a single wavelength
- 45why are slits rather than two separate light sources are used in young's double slitthe two separate light sources cannot form an interference pattern because the two light sources emit light waves at random. the points of cancellation and the points of reinforcement would change at random, so no interference pattern.
- 46using white light. fringe patternthe central fringe is white because every colour contributes at the centre of the pattern.
the blue fringe is closer to the central fringe than red because the blue fringe has a shorter wavelength than the red - 47single slit diffraction pattern
- 48double slit and single slit graph combined
- 49notes on the single slit graphthe central fringe is twice as wide as each of the outer fringes
the peak intensity of the fringes decreases with distance from the centre - 50the formula for width central diffraction fringe, w for a single slit diffractionw = wavelength x 2 x the slit-screen distance
/
the width of the single slit
remember the width of the central fringe is twice the others - 51in a diffraction grating what is the central beam calledthe zero order
- 52the angle of diffraction between each transmitted beam and the central beam increases if ...light of longer wavelength is used
a grating with closer slits is used - 53formula for diffraction grating
- 54what is the formula for the number of slits per metre on the gratingN = 1/ d ( distance between slits / grating spacing)
- 55how do you calculate the maximum number of orders producedn = d (sin(90) which is 1) / wavelength
always round to the nearest whole number - 56how many degrees in a minute1 degree = 60 minutes
- 57difference between stationary waves and progressive waves in terms of frequency , amplitude and phase difference.frequency.
for stationary waves all the particles except those at the node vibrate at the same frequency.
for a progressive wave all the particles vibrate at the same frequency.
amplitude
for stationary waves the amplitude vaires from zero at the nodes to a maximum at the antinodes.
for progressive waves the amplitude is the same for all particles.
phase difference.
for stationary waves the phase difference is equal to m pie, where m is the number of nodes between the 2 particles
for progressive phase difference = 2 pie d/ wavelength
where d is the distance apart
Informações
- Descrição
- A level Physics FlashCards sobre waves, criado por Mohamed Essa em 23-04-2017.
- Criado por
- Mohamed Essa · abr 2017
- Atualizado
- 5 jun 2017
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